25
How do we know these numbers? Record CO 2 emissions Measure CO 2 in the atmosphere Measure CO 2 in the oceans Estimate from small-scale land measurements Infer from spatial pattern and isotopes of atmospheric CO 2

26
How do we know these numbers? Record CO 2 emissions Measure CO 2 in the atmosphere Measure CO 2 in the oceans Estimate from small-scale land measurements Infer from spatial pattern and isotopes of atmospheric CO 2 Measure atmospheric O 2